Showing papers by "Mark Wilkinson published in 1997"
TL;DR: Double mutants that combine late-flowering mutations at four flowering-time loci with mutations at the LEAFY, APETALA1, AP1, and TERMINAL FLOWER1 loci showing a phenotype similar to that of ap1-1 or lfy-6 mutants grown under noninductive photoperiods suggest a redundant interaction with FLIP genes.
Abstract: We have analyzed double mutants that combine late-flowering mutations at four flowering-time loci (FVE, FPA, FWA, and FT) with mutations at the LEAFY (LFY), APETALA1 (AP1), and TERMINAL FLOWER1 (TFL1) loci involved in the floral initiation process (FLIP) Double mutants between ft-1 or fwa-1 and lfy-6 completely lack flowerlike structures, indicating that both FWA and FT act redundantly with LFY to control AP1 Moreover, the phenotypes of ft-1 ap1-1 and fwa-1 ap1-1 double mutants are reminiscent of the phenotype of ap1-1 cal-1 double mutants, suggesting that FWA and FT could also be involved in the control of other FLIP genes Such extreme phenotypes were not observed in double mutants between fve-2 or fpa-1 and lfy-6 ap1-1 Each of these showed a phenotype similar to that of ap1-1 or lfy-6 mutants grown under noninductive photoperiods, suggesting a redundant interaction with FLIP genes Finally, the phenotype of double mutants combining the late-flowering mutations with tfl1-2 were also consistent with the different roles of flowering-time genes
208 citations
144 citations
TL;DR: It is argued that lunglessness and the transition to cutaneous gas exchange is correlated with life in cold, montane, fast-flowing streams, and respiratory and cranial evolution are argued to be correlated, with the ventilatory function of the buccopharyngeal pump constraining the evolution of the skull.
Abstract: Atretochoana eiseltiis a radically divergent aquatic caecilian until recently known from only a single specimen from South America. In addition to its status as the largest lungless tetrapod known, and the only known lungless caecilian, this species has a suite of highly unusual morphological features that sets it apart from all other tetrapods, including sealed choanae (internal nostrils), complete loss of pulmonary arteries and veins, novel cranial architecture, and a novel stapedial muscle. The external, buccal, skeletal, muscular and cardiovascular anatomies ofAtretochoana eiseltiare described and compared to these features in other caecilians, particularly representatives of all typhlonectid genera which are its closest relatives. The comparative morphological data are used as a basis for interpretations of the ecology and evolution ofAtretochoana eiselti. It is argued that lunglessness and the transition to cutaneous gas exchange is correlated with life in cold, montane, fast-flowing streams. Here, high oxygen concentrations and reduced metabolic rate serve to relax the physiological limitations on body size imposed by a reliance upon cutaneous gas-exchange, and lungs can produce disadvantageous buoyancy. Cranial evolution has increased the gape ofAtretochoana eiseltirelative to other caecilians, and seems likely to be associated with a shift in prey size and possibly type. Several modifications of the cranium appear to be associated with enhanced cranial kinesis in which a distinct cheek unit is highly mobile. The novel stapedial musculature is interpreted as contributing to this cranial kinesis. Respiratory and cranial evolution are argued to be correlated, with the ventilatory function of the buccopharyngeal pump constraining the evolution of the skull. The evolution of lunglessness removed this constraint facilitating repatterning of the skull.
70 citations
TL;DR: Host tissue adjacent to tumour showed no obvious increase in vascular density with increasing proximity to the tumour edge, which suggests that tumour-released angiogenic factors are only effective over a short distance.
Abstract: For tumours to grow they must acquire an adequate blood supply, and the use of drugs to inhibit tumour vascularization is one promising approach to anti-cancer therapy. Clear information is therefore required on the vascular architecture of human tumours and animal tumour models used for testing anti-angiogenic therapies. Many previous studies on animal tumour models have shown that carcinomas are least vascular in their centres and that host tissues become more vascular with proximity to the tumour. However, we have previously found that many human colorectal carcinomas do not show this pattern. The present study on human oral squamous cell carcinomas (SCCs) again reveals significant differences. Paraffin sections from 24 SCCs were immunostained using the QBEnd-10 monoclonal antibody to demonstrate blood vessels, and these were quantified by interactive morphometry using a Kontron Videoplan system. In most carcinomas, viable tumour tissue was no less vascular in the tumour centre than in the tumour periphery. Although tumours are known to release angiogenic factors, viable tumour tissue was less vascular than adjacent host tissues. However, the tumour stroma, by itself, was more vascular than adjacent host tissues. Host tissue adjacent to tumour showed no obvious increase in vascular density with increasing proximity to the tumour edge, which suggests that tumour-released angiogenic factors are only effective over a short distance.
20 citations
Journal Article•
6 citations
Journal Article•
4 citations
TL;DR: The isthmian link, antitropicality and American biogeography: Distributional history of the AtherInopsinae (Pisces: Atherinidae).
Abstract: that cladograms match: A method of biogeographical inference. Syst. Zool. 36:175-195. SMITH, A. Gv A. M. HURLEY, AND J. C. BRIDEN. 1981. Phanerozoic paleocontinental world maps. Cambridge Univ. Press, Cambridge, England. STRANEY, D. Q 1982. Review of Advances in Cladistics: Proceedings of the First Meeting of the Willi Hennig Society, edited by V. A. Funk and D. R. Brooks. Syst. Zool. 31:337-341. SWOFFORD, D. L. 1993. PAUP: Phylogenetic analysis using parsimony, version 3.1. Illinois Natural History Survey, Champaign. THORSON, T. B., D. R. BROOKS, AND M. A. MAYES. 1983. The evolution of freshwater adaptation in stingrays. Natl. Geogr. Soc. Res. Rep. 15:663-694. THORSON, T. B., R. M. WOTTON, AND T. A. GEORGI. 1978. Rectal gland of freshwater stingrays, Potamotrygon spp. (Chondrichthyes: Potamotrygonidae). Biol. Bull. 154:508-516. WHITE, B. N. 1986. The isthmian link, antitropicality and American biogeography: Distributional history of the Atherinopsinae (Pisces: Atherinidae). Syst. Zool. 35:176-194. WILEY, E. O. 1988. Parsimony analysis and vicariance biogeography. Syst. Zool. 37:271-290.
1 citations
TL;DR: This paper presented a critique of these ideas, arguing that they are logically incoherent and that the method does not succeed in its aims and severely misrepresents the original arguments and the method, and amounts to no more than an attack on a straw man.
Abstract: Wilkinson (1991a) developed arguments that the distributions of primitive character states may delimit clades, and proposed a method that exploited the evidence of primitive character state distributions for inferring clades. Whiting and Kelly (1995) presented a critique of these ideas, arguing that they are logically incoherent and that the method does not succeed in its aims. This critique severely misrepresents the original arguments and the method, and amounts to no more than an attack on a straw man.